This invention relates to braking systems for vehicles, and more particularly to an exhaust braking system.
It is the general purpose of this invention to provide an engine braking exhaust system adaptable to an internal combustion engine including an exhaust line.
Exhaust braking systems of this type have as their object the retardation of moving vehicles by keeping the engine connected to the driving wheels in the usual manner through the transmission and operating the engine with a negative power output. The operation of braking is accomplished by permitting the throttle to assume its idle position and then blocking the exhaust pipe between the exhaust manifold and the muffler.
A system generally along these lines is disclosed in U.S. Pat. No. 2,924,205, which includes a damper placed in the exhaust line which may be appropriately positioned to block exhaust travel in the exhaust line. As stated in that patent, it is well known that the exhaust pressure in the line during the blocking operation may be built up to a value of 50 or 60 psi. It has been found that with such extremely high back pressure, a certain amount of valve train "float" and resulting valve train structural failure has occurred. It is the object of this invention to provide an engine exhaust brake which eliminates the amount of back pressure which can be built up in the exhaust systems to a level so as to avoid valve train "float" and possible resulting valve train structural failure.
Of more general interest in this area are U.S. Pat. No. 3,838,670, U.S. Pat. No. 3,234,923, and U.S. Pat No. 3,572,300, wherein no damper is utilized in the exhaust line. Also of general interest in this area is U.S. Pat. No. 2,876,876, disclosing a butterfly valve in the intake of the engine.